开发板：FL2440(nandflash:K9F1G08 128M)
编译器：arm-linux-gcc 4.3.2
二、原理分析 1. 硬件原理图分析。由原理图得知按键电路知，四个用户按键S2、S3、S4、S5分别接至2440的GPF0、GPF2、GPF3、GPF4，对应的终中断号依次是EINT0、EINT2、EINT3、EINT4，中断可由下降沿触发。
三、配置内核
make menuconfig来配置内核，这里由于前面的配置，只要加上字符驱动模块，即 Device Drivers ---> <*> Telephony support ---> Character devices --->
编译内核，并把编译好的内核下载到开发板上，运行：四、写驱动和测试程序：
编写适合fl2440开发板的按键驱动，文件名称：plat_button.c（代码在后面），编译生成plat_button.ko文件，并下载到开发板/目录下面。
编写按键测试程序，文件名称：s3c_button.c（代码在后面），并有gcc工具编译生成可执行文件s3c_button ，并下载到开发板/usr/sbin目录下。
五、加载和测试led驱动
[root@root /]#insmod plat_button.ko
[root@root /]# cat proc/devices
88 ttyUSB
189 usb_device
204 ttyS
252 button
253 led
254 rtc
[root@root /]# ls dev/
adc mtdblock2 tty tty46
audio mtdblock3 tty0 tty47
button mtdblock4 tty1 tty48
console mtdblock5 tty10 tty49
[root@root /]# s3c_button （测试运行程序后，按下按键）
KEY1 pressed.
KEY2 pressed.
KEY3 pressed.
KEY4 pressed.
至此按键驱动就添加好了。
以下是参考驱动和测试程序：
/*====================plat-button.c===============================*/
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/sysfs.h>
#include <linux/proc_fs.h>
#include <linux/rtc.h>
#include <asm/delay.h>
#include <linux/syscalls.h>
#include <linux/platform_device.h>
#include <linux/unistd.h>
#include <linux/irq.h>
#include <mach/regs-gpio.h>
#define DRV_AUTHOR "liuchengdeng<1037398771@qq.com>"
#define DRV_DESC "S3C24XX button driver"
/* Driver version*/
#define DRV_MAJOR_VER 1
#define DRV_MINOR_VER 0
#define DRV_REVER_VER 0
#define DEV_NAME ”button“
//#define DEV_MAJOR DEV_BUTTON_MAJOR
#ifndef DEV_MAJOR
#define DEV_MAJOR 0 /* dynamic major by default */
#endif
#define BUTTON_UP 0 /* Button status is up */
#define BUTTON_DOWN 1 /* Button status is pushed down */
#define BUTTON_UNCERTAIN 2 /* Button status uncerntain */
#define TIMER_DELAY_DOWN (HZ/50) /*Remove button push down dithering timer delay 20ms */
#define TIMER_DELAY_UP (HZ/10) /*Remove button up dithering timer delay 100ms */
static int debug = DISABLE;
static int dev_major = DEV_MAJOR;
static int dev_minor = 0;
/*============================ Platform Device part ===============================*/
/* Button hardware informtation structure*/
struct s3c_button_info
{
unsigned char num; /*Button nubmer */
char * name; /*Button nubmer */
int nIRQ; /*Button IRQ number*/
unsigned int setting; /*Button IRQ Pin Setting*/
unsigned int gpio; /*Button GPIO port */
};
/* The button plaotform device private data structure */
struct s3c_button_platform_data
{
struct s3c_button_info *buttons;
int nbuttons;
};
/* Button hardware informtation data*/
static struct s3c_button_info s3c_buttons[] = {
[0] = {
.num = 1,
.name = "KEY1",
.nIRQ = IRQ_EINT0,
.gpio = S3C2410_GPF(0),
.setting = S3C2410_GPF0_EINT0,
},
[1] = {
.num = 2,
.name = "KEY2",
.nIRQ = IRQ_EINT2,
.gpio = S3C2410_GPF(2),
.setting = S3C2410_GPF2_EINT2,
},
[2] = {
.num = 3,
.name = "KEY3",
.nIRQ = IRQ_EINT3,
.gpio = S3C2410_GPF(3),
.setting = S3C2410_GPF3_EINT3,
},
[3] = {
.num = 4,
.name = "KEY4",
.nIRQ = IRQ_EINT4,
.gpio = S3C2410_GPF(4),
.setting = S3C2410_GPF4_EINT4,
},
};
/* The button platform device private data */
static struct s3c_button_platform_data s3c_button_data = {
.buttons = s3c_buttons,
.nbuttons = ARRAY_SIZE(s3c_buttons),
};
struct button_device
{
unsigned char *status; /* The buttons Push down or up status */
struct s3c_button_platform_data *data; /* The buttons hardware information data */
struct timer_list *timers; /* The buttons remove dithering timers */
wait_queue_head_t waitq; /* Wait queue for poll() */
volatile int ev_press; /* Button pressed event */
struct cdev cdev;
struct class *dev_class;
} button_device;
static void platform_button_release(struct device * dev)
{
return;
}
static struct platform_device s3c_button_device = {
.name = "s3c_button",
.id = 1,
.dev =
{
.platform_data = &s3c_button_data,
.release = platform_button_release,
},
};
static irqreturn_t s3c_button_intterupt(int irq,void *de_id)
{
int i;
int found = 0;
struct s3c_button_platform_data *pdata = button_device.data;
for(i=0; i<pdata->nbuttons; i++)
{
if(irq == pdata->buttons[i].nIRQ)
{
found = 1;
break;
}
}
if(!found) /* An ERROR interrupt */
return IRQ_NONE;
/* Only when button is up then we will handle this event */
if(BUTTON_UP == button_device.status[i])
{
button_device.status[i] = BUTTON_UNCERTAIN;
mod_timer(&(button_device.timers[i]), jiffies+TIMER_DELAY_DOWN);
}
return IRQ_HANDLED;
}
static void button_timer_handler(unsigned long data)
{
struct s3c_button_platform_data *pdata = button_device.data;
int num =(int)data;
int status = s3c2410_gpio_getpin( pdata->buttons[num].gpio );
if(LOWLEVEL == status)
{
if(BUTTON_UNCERTAIN == button_device.status[num]) /* Come from interrupt */
{
//dbg_print("Key pressed!\n");
button_device.status[num] = BUTTON_DOWN;
printk("%s pressed.\n", pdata->buttons[num].name);
/* Wake up the wait queue for read()/poll() */
button_device.ev_press = 1;
wake_up_interruptible(&(button_device.waitq));
}
/* Cancel the dithering */
mod_timer(&(button_device.timers[num]), jiffies+TIMER_DELAY_UP);
}
else
{
//dbg_print("Key Released!\n");
button_device.status[num] = BUTTON_UP;
// enable_irq(pdata->buttons[num].nIRQ);
}
return ;
}
/*===================== Button device driver part ===========================*/
static int button_open(struct inode *inode, struct file *file)
{
struct button_device *pdev ;
struct s3c_button_platform_data *pdata;
int i, result;
pdev = container_of(inode->i_cdev,struct button_device, cdev);
pdata = pdev->data;
file->private_data = pdev;
/* Malloc for all the buttons remove dithering timer */
pdev->timers = (struct timer_list *) kmalloc(pdata->nbuttons*sizeof(struct timer_list), GFP_KERNEL);
if(NULL == pdev->timers)
{
printk("Alloc %s driver for timers failure.\n", DEV_NAME);
return -ENOMEM;
}
memset(pdev->timers, 0, pdata->nbuttons*sizeof(struct timer_list));
/* Malloc for all the buttons status buffer */
pdev->status = (unsigned char *)kmalloc(pdata->nbuttons*sizeof(unsigned char), GFP_KERNEL);
if(NULL == pdev->status)
{
printk("Alloc %s driver for status failure.\n", DEV_NAME);
result = -ENOMEM;
goto ERROR;
}
memset(pdev->status, 0, pdata->nbuttons*sizeof(unsigned char));
init_waitqueue_head(&(pdev->waitq));
for(i=0; i<pdata->nbuttons; i++)
{
/* Initialize all the buttons status to UP */
pdev->status[i] = BUTTON_UP;
/* Initialize all the buttons' remove dithering timer */
setup_timer(&(pdev->timers[i]), button_timer_handler, i);
/* Set all the buttons GPIO to EDGE_FALLING interrupt mode */
s3c2410_gpio_cfgpin(pdata->buttons[i].gpio, pdata->buttons[i].setting);
irq_set_irq_type(pdata->buttons[i].nIRQ, IRQ_TYPE_EDGE_FALLING);
/* Request for button GPIO pin interrupt */
result = request_irq(pdata->buttons[i].nIRQ, s3c_button_intterupt, IRQF_DISABLED, DEV_NAME, (void *)i);
if( result )
{
result = -EBUSY;
goto ERROR1;
}
}
return 0;
ERROR1:
kfree((unsigned char *)pdev->status);
while(--i)
{
disable_irq(pdata->buttons[i].nIRQ);
free_irq(pdata->buttons[i].nIRQ, (void *)i);
}
ERROR:
kfree(pdev->timers);
return result;
}
static int button_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct button_device *pdev = file->private_data;
struct s3c_button_platform_data *pdata;
int i, ret;
unsigned int status = 0;
pdata = pdev->data;
dbg_print("ev_press: %d\n", pdev->ev_press);
if(!pdev->ev_press)
{
if(file->f_flags & O_NONBLOCK)
{
dbg_print("read() without block mode.\n");
return -EAGAIN;
}
else
{
/* Read() will be blocked here */
dbg_print("read() blocked here now.\n");
wait_event_interruptible(pdev->waitq, pdev->ev_press);
}
}
pdev->ev_press = 0;
for(i=0; i<pdata->nbuttons; i++)
{
dbg_print("button[%d] status=%d\n", i, pdev->status[i]);
status |= (pdev->status[i]<<i);
}
ret = copy_to_user(buf, (void *)&status, min(sizeof(status), count));
return ret ? -EFAULT : min(sizeof(status), count);
}
static unsigned int button_poll(struct file *file, poll_table * wait)
{
struct button_device *pdev = file->private_data;
unsigned int mask = 0;
poll_wait(file, &(pdev->waitq), wait);
if(pdev->ev_press)
{
mask |= POLLIN | POLLRDNORM; /* The data aviable */
}
return mask;
}
static int button_release(struct inode *inode, struct file *file)
{
int i;
struct button_device *pdev = file->private_data;
struct s3c_button_platform_data *pdata;
pdata = pdev->data;
for(i=0; i<pdata->nbuttons; i++)
{
disable_irq(pdata->buttons[i].nIRQ);
free_irq(pdata->buttons[i].nIRQ, (void *)i);
del_timer(&(pdev->timers[i]));
}
kfree(pdev->timers);
kfree((unsigned char *)pdev->status);
return 0;
}
static struct file_operations button_fops = {
.owner = THIS_MODULE,
.open = button_open,
.read = button_read,
.poll = button_poll,
.release = button_release,
};
static int s3c_button_probe(struct platform_device *dev)
{
int result = 0;
dev_t devno;
/* Alloc the device for driver */
if (0 != dev_major)
{
devno = MKDEV(dev_major, dev_minor);
result = register_chrdev_region(devno, 1, DEV_NAME);
}
else
{
result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);
dev_major = MAJOR(devno);
}
/* Alloc for device major failure */
if (result < 0)
{
printk("%s driver can't get major %d\n", DEV_NAME, dev_major);
return result;
}
/* Initialize button_device structure and register cdev*/
memset(&button_device, 0, sizeof(button_device));
button_device.data = dev->dev.platform_data;
cdev_init (&(button_device.cdev), &button_fops);
button_device.cdev.owner = THIS_MODULE;
result = cdev_add (&(button_device.cdev), devno , 1);
if (result)
{
printk (KERN_NOTICE "error %d add %s device", result, DEV_NAME);
goto ERROR;
}
button_device.dev_class = class_create(THIS_MODULE, DEV_NAME);
if(IS_ERR(button_device.dev_class))
{
printk("%s driver create class failture\n",DEV_NAME);
result = -ENOMEM;
goto ERROR;
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
device_create(button_device.dev_class, NULL, devno, NULL, DEV_NAME);
#else
device_create (button_device.dev_class, NULL, devno, DEV_NAME);
#endif
printk("S3C %s driver version %d.%d.%d initiliazed.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
return 0;
ERROR:
printk("S3C %s driver version %d.%d.%d install failure.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
cdev_del(&(button_device.cdev));
unregister_chrdev_region(devno, 1);
return result;
}
static int s3c_button_remove(struct platform_device *dev)
{
dev_t devno = MKDEV(dev_major, dev_minor);
cdev_del(&(button_device.cdev));
device_destroy(button_device.dev_class, devno);
class_destroy(button_device.dev_class);
unregister_chrdev_region(devno, 1);
printk("S3C %s driver removed\n", DEV_NAME);
return 0;
}
/*===================== Platform Device and driver regist part ===========================*/
static struct platform_driver s3c_button_driver = {
.probe = s3c_button_probe,
.remove = s3c_button_remove,
.driver = {
.name = "s3c_button",
.owner = THIS_MODULE,
},
};
static int __init s3c_button_init(void)
{
int ret = 0;
ret = platform_device_register(&s3c_button_device);
if(ret)
{
printk(KERN_ERR "%s: Can't register platform device %d\n", __FUNCTION__, ret);
goto fail_reg_plat_dev;
}
dbg_print("Regist S3C %s Device successfully.\n", DEV_NAME);
ret = platform_driver_register(&s3c_button_driver);
if(ret)
{
printk(KERN_ERR "%s: Can't register platform driver %d\n", __FUNCTION__, ret);
goto fail_reg_plat_drv;
}
dbg_print("Regist S3C %s Driver successfully.\n", DEV_NAME);
return 0;
fail_reg_plat_drv:
platform_driver_unregister(&s3c_button_driver);
fail_reg_plat_dev:
return ret;
}
static void s3c_button_exit(void)
{
platform_driver_unregister(&s3c_button_driver);
dbg_print("S3C %s platform device removed.\n", DEV_NAME);
platform_device_unregister(&s3c_button_device);
dbg_print("S3C %s platform driver removed.\n", DEV_NAME);
}
module_init(s3c_button_init);
module_exit(s3c_button_exit);
module_param(debug, int, S_IRUGO);
module_param(dev_major, int, S_IRUGO);
module_param(dev_minor, int, S_IRUGO);
MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:S3C24XX_button");
/***********************************s3c_button.c*********************************************/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#define MAX_KEY_BUF 16
int main()
{
unsigned char buf[MAX_KEY_BUF];
int fd_key;
int ret;
fd_key = open("/dev/button", O_RDONLY);
if (fd_key == -1)
{
printf("open(fd_key) failed\n");
return -1;
}
while (1)
{
ret = read(fd_key, buf, MAX_KEY_BUF);
}
return 0 ;
}